Narelle Fraser is among Australia’s most distinguished police officers, having dedicated 15 years of her career to investigating some of the nation’s most appalling crimes – from child exploitation to terrorist attacks.

However, there is one case that has remained with her – that of the Mornington Monster, John Sharpe.

“I’ve never been able to understand or comprehend how John Sharpe not only murdered his pregnant wife Anna,” Fraser said, “but how he murdered his little girl Gracie.”

She added: “Little Gracie particularly suffered unimaginable pain and horror prior to finally relenting to the monster her father was.”

The case began in March 2004, when 41-year-old Anna Kemp was reported missing by her mother, Valerie, who was living in New Zealand, reports the Mirror.

She had been unable to reach Anna for several days and, when she questioned husband John Sharpe about her daughter’s whereabouts, he claimed she had absconded with another man.

Valerie was sceptical. However, when she received a series of suspicious texts on her birthday, which she said bore no resemblance to her daughter’s usual manner, she contacted the police.

Anna Kemp met John Sharpe whilst both were employed at the Commonwealth Bank in the 1990s. They wed in 1994 and relocated to the picturesque Victoria suburb of Mornington, where they welcomed their first daughter, Gracie, in 2002.

Gracie was born with hip dysplasia, a challenging medical condition that placed considerable pressure on the new parents.

However, when Kemp joyfully revealed a second pregnancy the following year, Sharpe became furious and suspicious, accusing his wife of being unfaithful.

He subsequently claimed he was afraid of being left alone to look after the couple’s disabled daughter.

Sharpe, who had been characterised as a “loner”, instantly became the police’s main suspect when an investigation was opened.

In an attempt to mislead them, he featured in a disturbing television interview, pleading with Kemp to return home whilst holding up a photograph of their daughter, Gracie.

However, police remained unconvinced and, after observing Sharpe’s questionable behaviour for several days, made an arrest.

In custody, Sharpe eventually confessed, recounting how he brutally killed his wife and daughter “like he was saying what he’d had for breakfast.”

According to Sharpe’s testimony, he had grown dissatisfied in his marriage and felt his wife was “controlling and moody”.

During this period, he purchased a high-powered speargun from a local fishing shop and began “practicing” with it in his back garden.

Upon discovering his wife’s second pregnancy, Sharpe became bitter and found she was “getting on his nerves”. After a row on 23 March 2004, he was unable to sleep.

As his wife lay soundly asleep in bed, he went to the back garden garage and retrieved his speargun. Returning to their bedroom, he launched a spear at his pregnant wife, missing her head by mere centimetres.

Kemp was still alive, so he fired a second, this one proving fatal. He then covered her body with towels and retired to sleep on the sofa downstairs.

Initially, he buried her body in the backyard. However, he soon decided this would not suffice and exhumed her corpse before dismembering her with an electric chainsaw and discarding the remains in bin bags along with the household rubbish.

At this point, Gracie was still alive. However, Sharpe was soon consumed by thoughts that his daughter “needed to be with her mum” and returned to the fishing shop with his infant daughter, where he would purchase the spear he would soon use to end her life.

On 27 March 2004, four days after brutally murdering his wife, Sharpe put Gracie to bed in her cot. After consuming several glasses of whiskey and Code to “numb his senses”, he fired four spears at the 19-month-old, including those he had used to kill his wife.

Once dead, Gracie too was discarded into a bin bag and disposed of like rubbish.

Police were later able to locate both bodies and Sharpe was convicted on two counts of murder in 2005. He will be eligible for parole in 2037.